Left handed material based on amorphous ferromagnetic microwires tunable by dc current

Tuning of the transmission characteristics of amorphous ferromagnetic microwires through a dc current is demonstrated. These structures are studied in the frequency region where they present double negative behavior. It is found that their frequency response shifts with small de currents circulating along the wires. It is observed that the dc current tends to compensate and even cancels the resonant peak associated to the static magnetic field applied along the wire axis. The phenomenon behind these findings is discussed in terms of the torque exerted by the field created by the current on the plane perpendicular to the wire axis. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3485055]